So, I just realized, Chaos Space Marines generate a Gift of the Gods at 10 Corruption (I thought it was 30, for some reason). I'm playing a Thousand Sons Sorcerer, which starts off with 16 Corruption, does this mean I roll for a Gift of the Gods at Character Creation?

Also, it says under the Sorcerer ability that I gain 1 Corruption for being a Sorcerer. Is that included in the +15 starting Corruption for a Thousand Sons, or do I begin with 16?

Edit: Also, I play on becoming Unaligned at some point. If I go from Tzeentch to Unaligned, and have a Gift which gives me a bonus for being Aligned to Tzeentch, do I keep the bonus, or does it just... disappear and give it's basic bonus?

1# Yes, you roll

2# You still have to add +1 corruption, so you start with 16

3# There were at least two topics about wheather GotG change when you become aligned/unaligned. Sadly I don't remember if there was any conclusion. GM's call but I'd say they should change when you became unaligned (gods don't like anyone abandoning them).

I rolled my Mutation, and woo, Tzeentch Tail. However, the wording confuses me. What does it mean by 'an additional attack'?

Do I get an extra attack when I attack? Or now that the game uses subtypes, does it mean I get an extra Attack subtype action? So, would I be able to use Doombolt and shoot a plasma pistol with my tail in the same turn?

For me it's more like additional, independent atack during your atack action (so you can shoot one more gun or swing one more sword - it's like two-weapon fighting without any need for talents) rather than extra atack action. For casting atack spells and shooting I'd say 'no, no'.

There was quite lengthy discussion on atacks and multiple atacks on this forum. Seek it out, also check the errata.

I read it as though you still need TWW (melee) to use it as part of an attack sequence with multiple attacks (right sword, left sword and tail), or you can use it by itself without TWW and multiple attack rules (you could still swift/lightning attack with the tail, and so on, just that you don't use your hands also). It's kinda like getting an additional attack from the Multiple Arms mutation, I'd assume.

It's a bit unclear though. Some clarification would probably be in order.

Look up "some rules clarification form ffg" topic. I think there as something about it there.